MRIConvert compilation on linux

seems buggy to set wxWidgets stuff,  comment it in CMakeLists.txt and set it manually with ccmake. For some reason, the cflags are used in linking comment. Remove it manually from command line.

#  INCLUDE (FindwxWidgets)

  SET(CMAKE_CXX_FLAGS " -DWX_PRECOMP ${CMAKE_CXX_FLAGS} ${wxWidgets_CXX_FLAGS}")

#  ADD_DEFINITIONS( ${wxWidgets_DEFINITIONS} ${PROJECT_DEFINITIONS} )